Administration of GS-5816 will be limited to 3 consecutive days to minimize the potential development of resistance. All subjects will be monitored for up to 48 weeks post-dose to determine the persistence of viral mutations. Twelve cohorts are planned for the examination; within each cohort subjects will receive QD doses of GS-5816 with safety, antiviral activity and pharmacokinetic assessments evaluated at specified time-points during the study